This invention relates to a spectral source, and more particularly to a spectral source for a polarized Zeeman atomic absorption spectrophotometer of the type of high frequency discharge which comprises a lamp having an anode and a cathode, and means for applying a magnetic field to the space formed between the anode and the cathode.
As a polarized Zeeman atomic absorption spectrophotometer excels in background correction, it is widely used for microanalysis of metal. Such a spectrophotometer is divided into two groups of types depending upon where the magnetic field is formed. The one is the type in which the magnetic field is formed in an atomizer for atomizing the sample to be analyzed. The other is the type in which the magnetic field is formed at the lamp of the spectral source. The former is inconvenient to fit a burner of the atomizer which is disposed between a pair of magnets because the space between the magnets is small, and also has a defect that the magnets become large in size so that the magnets are required to be disposed so as to surround the burner. The latter has a defect that, when a hollow cathode lamp of a spectral source including a hollow cathode and an anode is connected to D.C. power source, the life time of the lamp becomes short and the radiation intensity of the lamp considerably decreases. To improve the latter defect, it has been proposed to use a high-frequency source connected between the hollow cathode and the anode for establishing stabilized discharge therebetween.
A spectral source of this type is disclosed in U.S. Pat. No. 4,198,589. Essential disadvantage of this prior art resides in the fact that the life time of the lamp cannot be prolonged so long, as a result the lamp has some troubles in maintenance thereof.